5i'
PART I
Series N Recommendations
MAINTENANCE OF INTERNATIONAL SOUND-PROGRAMME
AND TELEVISION TRANSMISSION CIRCUITS
Blanc
MONTAGE: PAGE 2 = PAGE BLANCHE
SECTION 1
INTERNATIONAL SOUND-PROGRAMME TRANSMISSION
1.1 International sound-programme transmissions - Defini-
tions
Recommendation N.1
DEFINITIONS FOR APPLICATION TO INTERNATIONAL
SOUND-PROGRAMME TRANSMISSIONS
,
The following definitions apply to the maintenance of interna-
tional sound-programme transmissions. Other definitions are used
_________________________
Definitions in this Recommendation apply both to analo-
gue and digital systems.
Annex A to this Recommendation gives definitions for
units of measurements for sound-programme transmis-
sions.
for other purposes, e.g., an international sound-programme link and
international multiple destination sound-programme link as defined
in SS 11 and 12 respectively below, are within the definition of an
international sound-programme circuit as defined by the CMTT.
Note 1 - It is intended that the definitions given in
Recommendations N.1 and N.51 should remain identical, so far as is
practical, by use of only simultaneous amendments.
Note 2 - A sound-programme circuit section, circuit, link or
connection is considered to be permanent for maintenance purposes
if it is always available for use when required, whether or not it
is continuously in use. Such a circuit may be used for the purposes
of occasional transmission, that is, transmissions of short dura-
tion, e.g. less than 24 hours, or it may be used for a long dura-
tion, i.e. one day or more. A permanent sound-programme connection
between broadcasting organizations' premises may be used at any
time, except only for periods of maintenance as agreed between the
Administrations and broadcasting organizations concerned.
A sound-programme circuit section, circuit, link or connection is
considered to be temporary for maintenance purposes when it has no
existence outside the period of transmission (including line-up and
testing time) for which it is required.
1 international sound-programme transmission
The transmission of sound signals over the international
telecommunication network for the purpose of interchanging
sound-programme material between broadcasting organizations in dif-
ferent countries.
2 broadcasting organization
A broadcasting organization is an organization which is con-
cerned with either or both sound and television broadcasting. Most
of the customers ordering facilities for sound-programme and telev-
ision transmission are broadcasting organizations; for convenience,
the term broadcasting organization is used to denote the activity
of any user or customer and, where so used, it is equally applica-
ble to any other customer requiring sound-programme or television
transmissions.
3 broadcasting organization (send)
The broadcasting organization at the sending end of an inter-
national sound-programme transmission.
4 broadcasting organization (receive)
The broadcasting organization at the receiving end of an
international sound-programme transmission.
5 international sound-programme centre (ISPC)
A centre at which at least one international sound-programme
circuit (see S 9) terminates and in which international
sound-programme connections (see S 13) can be made up by the inter-
connection of international and national sound-programme circuits.
The responsibility of an ISPC is given in Recommendation N.5.
6 national sound-programme centre (NSPC)
A centre at which two or more national sound-programme cir-
cuits terminate and at which national sound-programme circuits may
be interconnected.
7 sound-programme circuit section
The unidirectional national or international sound-programme
transmission path between two stations at which the programme is
accessible at audio frequencies. The transmission path may be esta-
blished via terrestrial or single destination satellite routing.
(See Note 2 above and Figures 1/N.1 and 3/N.1.)
8 international multiple destination sound-programme circuit
section
The unidirectional sound-programme transmission path from one
frontier station to two or more of the frontier stations at which
interconnection is made at audio frequencies. (See Note 2 above and
Figure 4/N.1.)
9 international sound-programme circuit
The transmission path between two ISPCs which comprises one or
more sound-programme circuit sections (national or international),
together with any necessary audio equipment. The transmission path
may be established via terrestrial or single destination satellite
routing. (See Note 2 above and Figures 1/N.1 and 3/N.1.)
10 international multiple destination sound-programme circuit
The unidirectional transmission path from one ISPC to two or
more other ISPCs comprising sound-programme circuit sections
(national or international) one of which is an international multi-
ple destination circuit section, together with any necessary audio
equipment. (See Note 2 above and Figure 4/N.1.)
11 international sound-programme link
The unidirectional transmission path between the ISPCs of the
two terminal countries involved in an international sound-programme
transmission. The international sound-programme link comprises one
or more international sound-programme circuits (see Figures 1/N.1
and 3/N.1 below) interconnected at intermediate ISPCs. It can also
include national sound-programme circuits in transit countries.
(See Note 2 above and Figure 2/N.1.)
12 international multiple destination sound-programme link
The unidirectional transmission path between the ISPCs of the
terminal countries involved in an international multiple destina-
tion sound-programme transmission. The international multiple des-
tination sound-programme link comprises international
sound-programme circuits, one of which is an international multiple
destination sound-programme circuit. (See Note 2 above and
Figure 5/N.1.)
13 international sound-programme connection
The unidirectional transmission path between the broadcasting
organization (send) and the broadcasting organization (receive)
comprising the international sound-programme link extended at its
two ends over national sound-programme circuits to the broadcasting
organization. (See Note 2 above and Figure 2/N.1.)
14 international multiple destination sound-programme connection
The unidirectional transmission path between the broadcasting
organization (send) and two or more broadcasting organizations
(receive) comprising the international multiple destination
sound-programme link extended at its ends over national
sound-programme circuits to the broadcasting organizations. (See
Note 2 above and Figure 5/N.1.)
15 send reference station
The transmit sub-control station of an international multiple
destination sound-programme circuit section (see S 8), circuit (see
S 10) or link (see S 12). (See Figures 4/N.1 and 5/N.1.)
16 effectively transmitted signals in sound-programme
transmission
For sound-programme transmission , a signal at a particular
frequency is said to be effectively transmitted if the nominal
overall loss at that frequency does not exceed the nominal overall
loss at 800 Hz by more than 4.3 dB. This should not be confused
with the analogous definition concerning telephone circuits given
in the Recommendation cited in [1].
For sound-programme circuits , the overall loss (relative to
that at 800 Hz) defining effectively transmitted frequency is
1.4 dB, i.e. about one third of the allowance.
17 types of sound-programme circuit
The various types of international sound-programme circuit or
sections of such circuits should be referred to by quoting the top
nominal frequency, in kHz, effectively transmitted.
Example: 10-kHz sound-programme circuit.
Figure 1/N.1 p.
Figure 2/N.1 p.
Figure 3/N.1 p.
Figure 4/N.1 p.3
_________________________
To reduce problems in ordering and charging for
sound-programme circuits, Study Group II has a classif-
ication of circuits based on their approximate
bandwidth (see the Recommendation cited in [2]).
Figure 5/N.1 p.
ANNEX A
(to Recommendation N.1)
Level and loss units used for sound-programme
and television transmission
A.1 Use of dB units in N Recommendations
This Recommendation gives the quantities and units for
sound-programme transmissions used in N Recommendations and is in
accordance with existing Recommendations [3], [4].
A.2 Units used
A.2.1 absolute power level (dBm)
As a general rule, the dBm unit applies to the absolute power
level. The unit is based on the ratio between measured power and
the reference power of 1 mW.
Lm= 10 log fIP0
_____ dBm = 10 log U $$Ei:2:0_ /Z0)
________________ dBm =
|
|20 logfIU0
_____- 10 logfIZ0
_____|
| dBm
Absolute power level Absolute Impedance
voltage correction
level
Absolute voltage levels, for which terminal impedance is not
defined, are more rarely used. As a correction, power level may be
calculated for impedances other than 600 ohms, with respect to
1 mW.
The power level thus calculated would be equal to that meas-
ured in a correctly terminated system.
A.2.2 relative level (dBr)
_________________________
It is intended that the text contained in this annex
will be further studied and refined as necessary.
The relative power level of a point in a transmission system
is the nominal power gain at the reference frequency from a refer-
ence point to the point considered. The same consideration is used
for the relative voltage level in a transmission system based on
voltage levels.
Relative levels can be used to compare two or more points of a
network with respect to power (or voltage). One point of a network
is usually defined as the reference point at 0 dBr, from which
other measurement points are derived.
For sound-programme circuits, the zero relative level is
located at the injection point, i.e. usually at the transmission
point of a sound-programme circuit.
A.2.3 absolute zero power level (dBm0) (load level )
In a transmission system based on power levels the absolute
power level or load level (Lm\d0) with respect to 1 mW is referred
to a point of zero relative level. That means that the absolute
power level (Lm) minus the relative power level (Lr) will be
Lm\d0= Lm- Lr
This level indication is independent of the relative power
level at the measurement point considered. For a given signal the
load level is nominally the same along a transmission line. For
this indication it is necessary to know to what extent the power at
the zero relative point is greater or less than the reference
power.
A.2.3 absolute zero power level (dBm0) (load level )
In a transmission system based on power levels the absolute
power level or load level (Lm\d0) with respect to 1 mW is referred
to a point of zero relative level. That means that the absolute
power level (Lm) minus the relative power level (Lr) will be
Lm\d0= Lm- Lr
This level indication is independent of the relative power
level at the measurement point considered. For a given signal the
_________________________
The term "load level" is used provisionally and is sub-
ject to further consideration.
The term "load level" is used provisionally and is sub-
ject to further consideration.
load level is nominally the same along a transmission line. For
this indication it is necessary to know to what extent the power at
the zero relative point is greater or less than the reference
power.
A.2.4 Relation between quantities and units
There is a fixed relation between level quantities and units,
namely:
Absolute power level = relative power level + abso-
lute zero power level (load level)
Lm= Lr+ Lm\d0
Therefore, for the level units: a dBm = b dBr + c dBm0.
When indications are given concerning the line signal, the
absolute zero power level (load level) (dBm0) is given, at which,
at the relative zero point, the absolute power level coincides with
the relative power level.
Lm= Lm\d0, for Lr= 0
In order to simplify the specification of the level of a cir-
cuit or a system, it is most appropriate to specify the absolute
power level which coincides with the relative zero power level.
Thus this absolute power level and the absolute zero power level
(load level) are the same.
A.2.5 Weighted level
Power level of disturbing signals are as a rule expressed in
the same units as those defined above. For noise measurements made
by a weighting filter (psophometric measurements), a "p" (for
"pondere" = weighted) is added to the units, e.g., dbm0p, dBmp.
A "q" indicates a quasi-peak value where the "m" is replaced
by a "q" which, for instance, in dBm gives dBq.
A.2.6 Extra indications
Sound-programme transmission level units are indicated by an
extra "s" (s for sound): dBrs, dBm0s, dBm0ps, dBq0pS.
Extra indications for units should be used whenever they
facilitate understanding so as to prevent confusion when differing
measurement techniques, weighting filters or meters are used.
A.3 Various measuring instruments
Absolute power level (in dBm) is obtained if a measurement is
made on a terminated line.
Various measurement instruments provide measurements related
to a (freely) preselected relative level value. The measurement
will then directly express the absolute zero power level (load
level).
A.4 Practical problems
There is a wide range of measuring instruments used at dif-
ferent measurement points, so that differences are always bound to
appear. A state which every Administration is prepared to define is
the permitted maximum level (PML). Despite different relative power
levels, depending on the systems, a direct relation can now be
indicated between the value of the level to be measured and the PML
in dB. If, for instance, a signal of 21 dB below the PML is
transmitted as a measurement signal, it must also be received as a
signal 21 dB below PML, independently of local relative levels,
which may differ according to systems and Administrations.
References
[1] CCITT Recommendation General performance objectives
applicable to all modern international circuits and national exten-
sion circuits , Vol. III, Rec. G.151, Note 1, S 1.
[2] CCITT Recommendation Occasional provision of circuits
for International sound- and television-programme transmissions ,
Vol. II, Rec. D.180, S 3.
[3] CCITT Recommendation Use of the decibel and neper in
telecommunications , Vol. I, Rec. B.12.
[4] CCIR Recommendation Use of the decibel and neper in
telecommunications , Vol. XIII, Rec. 574, ITU, Geneva, 1986.
Recommendation N.2
DIFFERENT
TYPES OF SOUND-PROGRAMME CIRCUIT
The characteristics of the various types of international
sound-programme circuit defined in Recommendations J.21 [1], J.22
[2] and J.23 [3] are as follows:
15 kHz;
10 kHz;
5, 6.4 and 7 kHz.
From the point of view of sound-programme transmission ordi-
nary telephone circuits are generally considered to be suitable
only for the transmission of speech. It should be noted that the
limits of the
loss/frequency distortion cannot be guaranteed to be better
than the limits shown in Recommendation M.580 [4].
When a telephone circuit is used for a sound-programme
transmission the terminating sets and the signalling equipment must
be disconnected to avoid echo effects and false operation of the
signal receiver.
When a telephone circuit is used for a sound-programme
transmission, a point of zero relative level of the telephone cir-
cuit must coincide with a point of zero relative level on the
sound-programme circuit. (However, see S 2 of Recommendation N.15
in which it is pointed out that a 6-dB loss should be introduced in
order to reduce the mean power level delivered to the telephone
circuit system).
References
[1] CCITT Recommendation Performance characteristics of 15
kHz type sound-programme circuits , Vol. III, Rec. J.21.
[2] CCITT Recommendation Performance characteristics of 10
kHz type sound-programme circuits , Red Book, Vol. III, Rec. J.22,
ITU, Geneva, 1984.
[3] CCITT Recommendation Performance characteristics of
narrow-bandwidth sound-programme circuits , Vol. III, Rec. J.23.
[4] CCITT Recommendation Setting up and lining up an
_________________________
This Recommendation applies also to 7 kHz and 15 kHz
digital sound-programme circuits.
international circuit for public telephony , Vol. IV, Rec. M.580.
Recommendation N.3
CONTROL CIRCUITS
1 Definition of control circuit
A control circuit is a telephone-type circuit between the
point of origin of the programme and the point where it terminates
(recording equipment, studio, switching centre, transmitter, etc.)
used by a broadcasting organization for the supervision and coordi-
nation of a sound or television transmission.
More than one control circuit may be used in association with
the different programme connections involved in a single transmis-
sion, such as:
a) the television | onnection ;
b) the international sound | onnection (for
supervising the programme effects circuit provided for transmit-
ting, for example, the background noises of a programme);
c) the commentary | onnection (for supervising the
sound-programme circuit transmitting a commentary in a given
language);
d) the complete programme | onnection (for
supervising the sound-programme circuit transmitting the whole of
the sound part of a programme).
2 Provision of control circuits for sound-programme and
television transmission
The conditions governing the provisions and lease of control
circuits for sound-programme and television transmissions are given
in Recommendation D.180 [1].
_________________________
The CCITT has noted the fact that broadcasting organi-
zations use a tone having a frequency of 1900 Hz _ 6 Hz
and a level not exceeding -10 dBm0, for their signal-
ling purposes on control circuits. Under the conditions
of use specified in the CCITT Recommendations for con-
trol circuits, the CCITT has no objections to the use
of this tone.
Reference
[1] CCITT Recommendation Occasional provision of circuits
for International sound- and television-programme transmissions ,
Vol. II, Rec. D.180.
Recommendation N.4
DEFINITION AND DURATION OF THE LINE-UP PERIOD
AND THE PREPARATORY PERIOD
For each international sound-programme transmission a distinc-
tion is made between:
- line-up period
The period during which the Administrations line up the
international sound-programme link before handing it over to the
broadcasting organizations; and
- preparatory period
The period during which these broadcasting organizations
do their own adjustments, tests and other work before the
sound-programme transmission itself commences.
1 Line-up period
1.1 Duration
In principle, the duration of the line-up period should be
15 minutes. However, in the case of sound-programme transmissions
involving more than two countries, the duration may be increased.
On the other hand, in certain cases, by agreement between the
Administrations concerned, the duration may be less than
15 minutes, provided the line-up is properly carried out. This may
be possible, for example, when there are two successive interna-
tional sound-programme transmissions on the same route and the
second involves extending the international sound-programme link
already laid up for the first.
Note - In the case of multiple destination transmissions the
line-up period can have a longer duration, to be fixed by agreement
between the Administrations concerned, e.g., on the order of 25 to
30 minutes.
At the end of the line-up period the international
sound-programme link and the control circuits are handed over to
the broadcasting organizations at the booked time.
2 Preparatory period
2.1 Beginning and duration
When the tests during the line-up period are completed, the
international sound-programme link is not made available to the
broadcasting organizations at the two ends until the time fixed for
the beginning of the preparatory period. The chargeable time for
the sound-programme transmission commences at the beginning of the
preparatory period. The duration of the preparatory period - i.e.
the time between handing over the international sound-programme
link to the broadcasting organizations and the moment when the pro-
gramme properly begins - is chosen in each case by the broadcasting
organizations so that they can carry out all the tests and adjust-
ments necessary before proceeding with the sound-programme
transmission.
Recommendation N.5
SOUND-PROGRAMME CONTROL, SUB-CONTROL AND |
SEND REFERENCE STATIONS
1 Responsibilities of control and sub-control stations
1.1 For a unidirectional international sound-programme cir-
cuit, the receiving end terminal ISPC is normally the control sta-
tion. The other terminal ISPC is a terminal sub-control station.
The functions of the control and sub-control stations are the same
as for ordinary telephone circuits. (See Recommendations M.80 [1]
and M.90 [2].)
Note - In the case of a reversible sound-programme circuit,
setting-up reference measurements and maintenance measurements are
carried out for each direction of transmission.
1.2 The international sound-programme link is in all cases the
sole responsibility of the telephone Administrations. If the inter-
national sound-programme link passes through one or more transit
countries, an intermediate sub-control station is also designated
for each transit country.
1.3 The national sound-programme circuits at the ends of the
link may be the responsibility of either the Administrations or the
broadcasting organizations or the two together depending on local
arrangements in each particular country.
1.4 The receiving ISPC stations on multiple destination
sound-programme circuits or links act as control stations for the
circuit or link in accordance with Recommendations M.80 [1] and
M.90 [2]. In this case the following additional responsibilities
should apply:
a) reporting to the appropriate send reference sta-
tion (see S 2) the results of measurements made on the circuit and
link and the quality assessments observed on the link;
b) reporting fault conditions to the circuit or
link send reference station (see S 2).
1.5 The intermediate ISPCs are intermediate sub-control sta-
tions for the international sound-programme link.
1.6 The ISPC or the repeater station at the sending end (coun-
try A in Figures 2/N.1 and 5/N.1) is a terminal sub-control sta-
tion for the international sound-programme connection. When a send
reference station (see S 2) is associated with a multiple destina-
tion communications-satellite link, it has the following responsi-
bilities:
a) coordination of lining up the
multiple-destination sound-programme circuit sections, circuits and
links, respectively;
b) keeping a record of the measurements made during
the lining-up period of the circuit section, circuit or link, and
recording the quality assessments observed at control stations dur-
ing the lining-up of the link;
c) relevant maintenance action for the sub-control
and control stations at the request of one of these stations.
However, the choice of the station nominated as the terminal
sub-control station is left to the discretion of the Administration
concerned.
1.7 Exchange of contact point information on sound-programme
transmission should be made in accordance with
Recommendation M.93 [3].
2 Send reference stations
Sound-programme transmissions provided on a multiple destina-
tion basis using a communication satellite system, differ from
those using only terrestrial facilities in that the common
transmitting path extends through the transmitting earth station to
the satellite. The receiving paths extend from the satellite
through the receiving earth stations concerned to the terminal ISPC
control stations.
Operations on the common path of the connection affect all
receiving stations, whereas on any of the other paths the opera-
tions affect only the one receiving terminal station involved.
These distinctive features of a multiple destination
sound-programme transmission provided in the above manner require
the assistance of certain stations designated as send reference
stations.
Send reference stations are situated along the common path of
the sound-programme circuit or link and are identified as follows:
a) a sub-control station located at the transmit-
ting terminal of the circuit section containing the space segment;
b) the terminal sub-control stations for the cir-
cuit and link containing the space segment.
Figure 4/N.1 shows the basic composition for a multiple desti-
nation sound-programme circuit routed via a communication satellite
system. The send reference stations are shown as R and R` for the
multiple destination circuit section and circuit respectively.
Figure 5/N.1 shows the basic composition for a multiple desti-
nation sound-programme link and connection routed via a communica-
tion satellite system. The send reference stations are shown as R`
and R" for the multiple destination circuit and link respectively.
References
[1] CCITT Recommendation Control stations , Vol. IV,
Rec. M.80.
[2] CCITT Recommendation Sub-control stations , Vol. IV,
Rec. M.90.
[3] CCITT Recommendation Exchange of contact point informa-
tion for the maintenance of international services and the interna-
tional network , Vol. IV, Rec. M.93.
1.2 Setting-up, lining-up and monitoring the international
sound-programme links and connections
It is assumed that the international sound-programme
connection is as shown in Figure 2/N.1. It is also assumed that the
various sound-programme circuits to be interconnected to constitute
the international sound-programme link are circuits established and
maintained as given in Subsection 1.3 below.
Recommendation N.10
LIMITS FOR THE LINING-UP OF INTERNATIONAL
SOUND-PROGRAMME LINKS AND CONNECTIONS
1 General
This Recommendation gives limits in Tables 1/N.10 to 5/N.10
for the lining-up of international sound-programme links as defined
in Recommendation N.1. These limits correspond to those for three
audio sections of the hypothetical reference circuit as defined in
CCIR Recommendation 502 [1] for 5 kHz, 6.4 kHz, 7 kHz and 10 kHz
type sound-programme circuits, but correspond to four audio sec-
tions for 15-kHz type sound-programme circuits except for noise
limits, which correspond to three audio sections [2]
It is not possible at the present time to recommend limits for
the sound-programme connection. However, Administrations shall
endeavour to provide national sound-programme circuits to as high a
standard as possible so that the performance of the sound-programme
connection is not markedly different to that of the sound-programme
link.
Some Administrations arrange their apparatus in an ISPC so
that at the point of interconnection the output impedance of every
receive channel or circuit over the frequency band of interest is
substantially lower than the input impedance of any send channel or
circuit. This is the so-called constant-voltage technique impedance
match at the point of interconnection and choose the value of this
impedance to be equal to the design resistance of measuring instru-
ments. This is known as the impedance-matching technique (previ-
ously referred to as the constant electromotive force technique ).
It should be noted that in both cases the through-level measurement
results relative to the through-level at 800 Hz will be the same.
Furthermore the terminated-level measurement results relative to
the terminated-level at 800 Hz will also be the same value
Hence the limits recommended in the following tables are
_________________________
Wider tolerance limits are recommended for 15-kHz type
sound-programme circuits because of performance limita-
tion of commercial equipment.
This depends on the almost constant ratio of the im-
pedances on the send and receive sides at the various
frequencies. (See S 4 of Recommendation N.11.)
applicable regardless of the arrangement adopted by Administrations
at their ISPCs.
The test procedures are described in Recommendation N.21. The
limits for 15 kHz and 7 kHz circuits are applicable both for analo-
gue and digital transmissions.
2 Limits for the loss/frequency distortion of an interna-
tional sound-programme link
The majority of international sound-programme links are in
practice established with three or less circuits in series.
Many links could be established without additional equalizers
but links comprising four or more circuits will probably require
equalization. In this case the opportunity could again be taken to
obtain as good a loss/frequency characteristic as possible.
H.T. [1T1.10]
TABLE 1/N.10
Limit for the lining-up of 15 kHz sound-programme links
___________________________________________________________________________________________
Item Parameter Unit Limits
___________________________________________________________________________________________
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{
TABLE 1/N.10 (cont.)
}
Item Parameter Unit Limits
{
{
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{
14
Intelligible crosstalk ratio A/B
dB
48
}
{
15
Crosstalk ratio (intermodulation) A/B
dB
58
MONTAGE:
Additional parameters
for stereo transmission
}
___________________________________________________________________________________________
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Table 1/N.10 [1T1.10], p.
H.T. [2T1.10]
TABLE 1/N.10 (cont.)
_____________________________________________________________________________________________
Item Parameter Unit Limits
{
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{
14
Intelligible crosstalk ratio A/B
dB
48
}
{
15
Crosstalk ratio (intermodulation) A/B
dB
58
MONTAGE:
Additional parameters
for stereo transmission
}
_____________________________________________________________________________________________
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Table 1/N.10 (cont.) [2T1.10], p.
H.T. [T2.10]
TABLE 2/N.10
Limits for the lining-up of 10 kHz sound programme
links
__________________________________________________
Item Parameter Unit Limits
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Table 2/N.10 [T2.10], p.
H.T. [T3.10]
TABLE 3/N.10
Limits for the lining-up of 7 kHz sound-programme links
__________________________________________________
Item Parameter Unit Limits
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Table 3/N.10 [T3.10], p.
H.T. [T4.10]
TABLE 4/N.10
Limits for the lining-up of 6.4 kHz sound-programme links
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Item Parameter Unit Limits
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Table 4/N.10 [T4.10], p.
H.T. [T5.10]
TABLE 5/N.10
Limits for the lining-up of 5 kHz sound-programme links
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Item Parameter Unit Limits
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Table 5/N.10 [T5.10], p.
References
[1] CCIR Recommendation Hypothetical reference circuits for
sound-programme transmissions , Vol. XII, Rec. 502, ITU, Geneva,
1986.
[2] CCIR Recommendation Estimation of transmission perfor-
mance of sound-programme circuits shorter or longer than the
hypothetical reference circuit , Vol. XII, Rec. 605, ITU,
Geneva, 1986.
[3] CCIR Recommendation Performance characteristics of
10 kHz type sound-programme circuits , Vol. XII, Rec. 504, ITU,
Geneva, 1982.
Recommendation N.11
ESSENTIAL
TRANSMISSION PERFORMANCE OBJECTIVES FOR
INTERNATIONAL SOUND-PROGRAMME CENTRES (ISPC)
1 Transmission level at interconnection points
Levels at interconnection points must be such that a signal
level of 0 dBm0 on the incoming circuit gives rise to a signal
level of 0 dBm0 on the outgoing circuit. A nominal relative level
of +6 dBr is recommended at interconnection points (see also
Figure 3/J.13 [1] and Recommendation J.14, S 1 [2]).
2 Balance with respect to earth
The balance with respect to earth (measured by the method
defined in [3]) of nominally balanced apparatus should be at least
60 dB in order to give an adequate suppression against longitudinal
interference induced by power supplies, alarm circuits, etc.
3 Access points
There should be a well-defined circuit access point associated
with the input to a sound-programme circuit at which the transmis-
sion test levels at all frequencies over the band are nominally the
same. This access point may be the interconnection point or
separated therefrom by distortion-free loss or gain. A well-defined
circuit access point should also be associated with the output of a
sound-programme circuit.
The nominal relative level at each access point will be chosen
by each Administration, bearing in mind the dynamic range of their
testing and transmission apparatus.
Measurements on a sound-programme circuit should be made
between such circuit access points.
Administrations may also find it convenient to arrange for
sound-programme circuit sections to be equipped with similar access
points. International sound-programme circuit sections which can
be connected to a variety of other circuit sections should always
be equipped with such access points.
4 Interconnection of sound-programme circuits
4.1 Constant voltage technique
If the modulus of the output impedance of any source is not
greater than one hundredth of the modulus of the lowest impedance
that can be connected to it (bearing in mind that it is possible to
connect two or more loads in parallel) then the change in level due
to change of load will be negligibly small (less than 0.1 dB
approximately).
4.2 Impedance matching technique
If the return loss versus the nominal design resistance of the
measuring instruments of the impedance presented by incoming and
outgoing circuits to the points where they are interconnected is at
least 26 dB over the range 50 Hz to 10 or 15 kHz, the error due to
mismatch will be insignificant, assuming that the impedance of
testing apparatus has at least 30-dB return loss versus the nominal
design resistance, which can be, for example, 600 ohms
non-reactive.
4.3 Digital technique
The interconnection of digital sound-programme circuits will
be made by preference with the aid of a digital interface present-
ing the following characteristics:
- plesiochronous or synchronous operation
- bit rate of 384 kbit/s, 1544 kbit/s or
2048 kbit/s
- 384 kbit/s to carry either one 15 kHz or two
7 kHz sound-programme signals.
Interface for other bit rates, namely to provide for 15 kHz
monophonic and stereophonic circuits with linear coding and for
7 kHz monophonic sound-programme circuits with companded coding are
the subject of further study.
References
[1] CCITT Recommendation Definitions for international
sound-programme circuits , Vol. III, Rec. J.13.
[2] CCITT Recommendation Relative levels and impedances on
an international sound-programme connection , Vol. III, Rec. J.14.
[3] CCITT Recommendation Transmission aspects of unbalance
about earth Vol. III, Rec. G.117.
Recommendation N.12
MEASUREMENTS TO BE MADE DURING THE LINE-UP PERIOD
THAT PRECEDES A SOUND-PROGRAMME TRANSMISSION
After the connection of the various circuits to form the
international sound-programme link (conforming to the level
diagrams of these circuits) it is necessary to verify, by means of
an automatic measuring equipment (see Recommendations
O.31 [1], O.32 [2] and O.33 [3]) or by measurements at individual
frequencies, that the received level at the distant incoming termi-
nal ISPC is at the correct value (see Recommendation N.10) at the
following frequencies:
for an international sound-programme link composed entirely
of 15-kHz sound-programme circuits 40, 800 and 15 | 00 Hz | 1)
for an international sound-programme link composed entirely of
10-kHz sound-programme circuits 50, 800 and 10 | 00 Hz | 1)
for an international sound-programme link comprising at least one
7 kHz sound-programme circuit 50, 800 and 7 | 00 Hz | 1)
for an international sound-programme link comprising at least one
6.4-kHz sound-programme circuit 50, 800 and 6 | 00 Hz | 1)
for an international sound-programme link comprising at least one
5 kHz sound-programme circuit 100, 800 and 5 | 00 Hz | 1)
for an international sound-programme link comprising at least one
ordinary telephone circuit 300, 800 and 3 | 00 Hz
The send level during these measurements should be -12 dBm0.
In the case of 15-kHz sound-programme links forming a stereo-
phonic pair, it is necessary to verify the interchannel parameter
limits specified in Table 4/N.10.
A measurement of other parameters such as nonlinear distortion
and noise should be measured on all links and the results recorded.
At the present time the limits cannot be specified.
The national sound-programme circuits should be so adjusted
that, when they are connected to the international sound-programme
link, the level diagrams of the international sound-programme cir-
cuits are respected. In this regard, a useful and quick method
which Administrations could use to verify the correct alignment of
sound-programme links is given in Annex A of Recommendation N.13.
Any necessary adjustments having been made, the national cir-
cuits are connected to the international sound-programme link at
the terminal ISPCs. This is the end of the line-up period and the
beginning of the preparatory period and is the instant when the
complete connection is placed at the disposal of the broadcasting
organizations.
The latter then proceed to measure and adjust as necessary.
References
[1] CCITT Recommendation Automatic measuring equipment for
sound-programme circuits , Vol. IV, Rec. O.31.
[2] CCITT Recommendation Automatic measuring equipment for
stereophonic pairs of sound-programme circuits , Vol. IV,
Rec. O.32.
[3] CCITT Recommendation Automatic equipment for rapidly
measuring stereophonic pairs and monophonic sound-programme cir-
cuits, links and connections , Vol. IV, Rec. O.33.
_________________________
Or the frequency appropriate to the telephone-type cir-
cuit used.